Method of treating fibrous material



No Drawing.

Patented Dec. 18 192s.

UNITED STATES- PATENT OFFICE..

ARTHUR L. BROWN, 0] WILKINSB'URG, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC 8a MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- vama I This invention relates to synthetic resins,

more particularly .to a method of. treating Tof were then molded-under suitable condibeing treated.

tions of heat and pressure to provide a laminated product.

This procedure was expensive in that the solution used for impregnation generally contained about 70% of solvent which was lost in the drying operation. The varying atmospheric conditions of temperature and moisture content caused irregular variations in the amount of solution of resin taken up by the material being treated.

It is among the objects of my invention to obviate thedisadvantages of prior methods of treating materials to be molded and to rovide a method of treating the same where- 1n the use of solvents is eliminated and in which at least a part of the condensation reaction takes place in the fibres of the material In practising my invention, I generally impregnate the sheet material with a catalytic agent, such, for instance, as hexa-methylene tetramine, commonly known as hexa, in alcohol or water solution. The water or alcohol is then evaporated and the material is passed through-the ingredients of a condensation product which may be phenol in formaldehyde. or its equivalent, 'or, preferably, a mixture of a phenolic body, such as cresol, formaldehyde or its polymers and a polymerizable oil, such as Chlna' wood oil. The sheet material so impregnated is then passed through a tower at a suitable temperature to promote the reaction until the material is approximatelydry. y

As a specific example of the operation of my process, I provide a roll of paper or fabric which is drawn through a bath containin a 10% solution of hexa in 40% formalde yde or a weaker solution of formaldehyde,

METHOD OF TREATING FIBROUS MATERIAL.

Application filed March 16, 1923. Serial No. 625,625..

if desired, and I then pass the paper through a tower at a temperature slightly above the boiling point of water to dry the material. Part of the formaldehyde used vaporizes in the drying process but a large proportion of it polymerizes in the fibre and remains as solid para-formaldehyde together with the hexa. The treated paper is passed through a mixture of 20% raw China wood oil and 80% cresol, previously treated with-a small amount of formaldehyde or its polymers. The impregnated paper is then passed through a tower heatedto 100 0., or slightly above, until the tackiness of the paper has disap peared. A soluble condensation product is thus formed in the paper which, when treated by heat and pressure, may be converted into the insoluble form, as is ordinarily practised in the art. I

I prefer to omit the formaldehyde from the above described preliminary treatment of the materials and merely impregnate the paper with hexa and pass the same through an incompletely condensed phenolic material or partially formed condensation prod uct and thendry the same at about 100 C.

In another modification of my process, I may utilize a solution of a condensation product of the above described character in a solvent, such as benzol, which does not appreciably dissolve hexa. I have found that a benzol solution of a potentially infusible phenolic-formaldehyde condensation product formed of, cresol and China wood oil as ingredients thereof may beused for impregnating paper or the like Which has previously been impregnated or treated with hexa, without removing any appreciableamount of hexa from the paper, I have also been able to'make a solution of condensation product, add hexa thereto and impregnate the material with the mixture.

However, I prefer to first impregnate the sheet material with the hexa and then pass the same through the condensation product or the ingredients thereof, or both.

My method has distinct advantages over processes previously used in that a condensation product may be formed in the sheet material and no vacuum equipment is necessary to remove water, as the amount of water formed in the reaction is negligible. It is unnecessary to thicken the product after the condensation reaction has taken place. In the preferred modification, no solvent is used for the condensation product, thus avoiding the expense of solvent and of the heat necessary to vaporize the same.

Although I have described several specific embodiments of my invention, it is to be understood that my invention is not limited by the examples set forth, said examples being for purpose of illustration only.

I claim as my invention:

1. A method of treating fibrous material which comprises impregnating the same with a catalytic agent, impregnating the treated material with a mixture comprising a phenolio body and a polymerizable oil and then heating.

y 2. Amethod of treating fibrous material which comprises impregnating the same with a catalytic agent, impregnating the treated material with a liquid mixture comprising a phenolic body and a polymerizable oil, previously treated with a substance containing a methylene group and then heating.

3. A method of treating fibrous material a K which comprises impregnating the same w1th a catalytic agent, impregnating the treated material with a mixture comprising a phenolic body, formaldehyde and a polymerizable oil, and then heating.

4. A method of treating fibrous material which comprises impregnating the same with hexa-methylene-tetramine, impregnating the treated material with a mixture comprising a solution of a catalytic agent, evaporating.

the solution, impregnating the treated material with a mixture comprising a phenolic body, formaldehyde and a polymerizable oil and then heating.

In testimony whereof, I have hereunto subscribed my name this 14th day of March, 1923.

ARTHUR L. BROWN, 

